Cavernous malformation of the brainstem.
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Cavernous Malformations
Cavernous malformations are abnormal clusters of blood vessels embedded in normal brain tissue. Most cavernous malformations occur sporadically, but in certain cases they can be hereditary. Cavernous malformations are also known as cavernous hemangiomas or cavernomas. They can occur anywhere in the central nervous system. Because they are low-pressure lesions, cavernous malformations can leech blood into the surrounding brain, causing the acute onset of neurological deficits. These lesions compose about 5% of all vascular lesions of the brain. However, they are only found in about 0.1% of the general population.
Signs and Symptoms
The most common presenting signs are seizures, focal neurological deficits, and brain hemorrhage (bleeding). Despite the significant deficits that can develop after a cavernous malformation hemorrhages, patients often improve dramatically over time. However, repeated hemorrhages can produce a stepwise deterioration with subsequent permanent deficits, including paralysis, weakness, numbness, dysesthetic nerve pain, visual loss, memory deficits, speech impairment, and coordination difficulties. Although the natural history of cavernous malformations is still being defined, their annual hemorrhage rate is relatively low at 0.2 to 2% per year. However, brainstem cavernous malformations appear to be associated with a higher hemorrhage rate than lesions in other parts of the brain.
Cavernous malformations can be diagnosed on the basis of magnetic resonance (MR) imaging alone. Some patients, however, undergo computed tomography (CT) angiography or catheter-based angiography to rule out other possible conditions.
Venous Anomalies
Venous anomalies are frequently identified in tandem with cavernous malformations. These lesions are enlarged venous structures that drain normal brain tissue. They can be visualized on contrast-enhanced MR images near the cavernous malformation. The classic appearance is called a caput medusae (medusa's head). Venous anomalies can also occur in patients who do not have a cavernous malformation. These lesions seldom require surgical intervention. In fact, resection of a venous anomalies associated with a cavernous malformation can have devastating consequences and should be avoided.
Treatment
The location of the cavernous malformation and the patient's clinical history dictate specific treatment recommendations. Symptomatic lesions and those that are epileptogenic are frequently candidates for microsurgical treatment. We prefer microsurgical resection for surgically accessible and symptomatic cavernous malformations. We do not recommend stereotactic radiosurgery for the treatment of cavernous malformations.
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